Proventricular Dilatation Disease (PDD) occurs in several bird species (for example psittaciformes, accipitridiformes, columbiformes, anseriformes) and in particular in parrots (psittacides) wherein the disease is often fatal. Even if the disease was discovered three decades ago, its etiopathogenesis is still unclear.
Proventricular Dilatation Disease (PDD) was disclosed for the first time in the USA at the end of '70 in the genus Ara. Nowadays it is worldwide widespread, and it is observed in more than 50 species of psittacides, but also in Canadian gooses and in some birds of prey, but with very low frequency.
After several years form the discovery of PDD and in spite of the several study groups around the world, the etiologic agent is still un-isolated and un-clarified, even if the most acknowledged agent is a neurotropic virus, such as Paramyxovirus, and, in the last months, Bornavirus.
The disease shows two main types of symptoms: gastrointestinal disorders (undigested food in feces, regurgitation, and weight loss) and central nervous system disorders (tremors, instability, in-coordination, loss of balance), both presenting polyneuritis at a histological level and both often leading to death.
Besides the fragmentary knowledge on etiology, also the therapeutic protocol is incomplete. FANS are the top grade class of drugs used and they give unsatisfactory, and not resolving at long term, therapeutic results.
Nowadays, the in vitam methods for the diagnosis of Proventricular Dilatation Disease (PDD) are: endoscopy, radiography and biopsy.
Even if so many diagnostic tests are available, the only reliable method is biopsy, but it is poor sensible (40% of false negative) and it is dangerous for the subject undergoing to examination.
Nowadays, the diagnostic methods known in the art are all quite invasive and require the subject to be anesthetized, and thus they are risky and expensive for the animal's owner. At the same time, said methods do not give a definitive diagnosis since they cannot distinguish with absolute certainty between healthy and suffering subjects. In addition, they need surgical and stressful operations to be performed on the subjects undergoing to examination, which are at risk of death when they are already wasted by the disease.
Up until few years ago, Proventricular Dilatation Disease—PDD was poorly present and widespread in Italy, but frequently disclosed internationally. Now, the disease is occurring with a higher frequency and indistinctly affecting several species of parrots having different economic values.
Rarely the disease affects animals with a commercial value of around few tens of Euros, while it mainly affects Australian or South-Americans parrots of big size and high economic value (many tens of thousands of Euros) causing severe commercial losses and hardly damaging the worldwide commerce of said species.
Furthermore, an other aspect to be considered is that the disease can affect rare species of psittaciformes which count few tens of individuals (Spix's Macaw) and can further reduce the number of animals.